MARRAKECH, MOROCCO -- French President Francois Hollande on Tuesday urged the United States to respect the “irreversible” Paris Agreement on climate change, and said France will lead a dialogue on the topic with President-elect Donald Trump“on behalf of the 100 countries that have ratified” the deal.

Speaking to a U.N. climate conference in Morocco, Hollande praised President Barack Obama for his role in getting the landmark deal adopted by more than 190 countries in the French capital last year.

“The United States, the most powerful economy in the world, the second-largest emitter of greenhouse gases, must respect the commitments that were made,” he said. “It’s not simply their duty, it’s in their interest.”

Scientists say oil and other fossil fuels are the biggest contributors to man-made warming. Trump, however, has called global warming a “hoax” and pledged during his campaign to “cancel” the Paris deal.

Earlier, U.N. Secretary-General Ban Ki-moon said he hopes Trump will shift his course on global warming and “understand the seriousness and urgency” of addressing the problem.

“As president of the United States, I’m sure that he will understand this, he will listen and he will evaluate his campaign remarks,” Ban told reporters in Marrakech.

The Paris Agreement was signed by more than 190 countries and has been formally approved by more than 100 of them, including the United States and even oil-rich Saudi Arabia.

Ban called international climate action “unstoppable” and said that no country, “however resourceful or powerful,” is immune from the impacts of global warming.

“We have no right to gamble with the fate of future generations — or imperil the survival of other species that share our planet,” Ban told the conference.

Trump’s election has created uncertainty about the U.S. role in the Paris deal, which calls on all countries to reduce or curb their greenhouse gas emissions and encourages rich countries to help poor ones deal with climate change.

King Mohammed VI of Morocco urged delegates at the conference to translate their commitments into actions.

“What’s at stake is the very existence of man,” the king said. “It is therefore our joint duty to work hand in hand to protect humanity.”